Phil. Trans. R. Soc. A 373, 20130040 (2014)

Climate change is having different temperature impacts on the two polar regions. While the Arctic is warming at a greater rate than elsewhere, the Antarctic has predominantly experienced cooling and sea-ice expansion. John Marshall, of Massachusetts Institute of Technology, USA, and colleagues investigated this phenomenon by considering the role the ocean may play.

The authors consider how differences in ocean circulation — with surface waters sinking to depth in the high-latitude North Atlantic compared with upwelling of deep waters around Antarctica — influence the response of sea surface temperatures, and therefore atmospheric temperature, to greenhouse gas and other forcings. Although the two regions are subjected to similar greenhouse gas forcing, the Antarctic is also experiencing ozone depletion.

They conclude that at present the cooling of the Antarctic is associated with effects related to ozone depletion in the region, which is cancelling the warming due to greenhouse gases. They suggest that this is a short-term effect, as ozone recovers and adds to the warming. In contrast, the Arctic is experiencing warming that is enhanced by ocean heat transport and this is expected to continue.